Thread: Car cranks but no start. Fuel injectors not releasing gas

Originally Posted by Shiftingshaddow

Would the fuel pump, if already weak, just not be able to give enough pressure if it hadnt been used in over a week? The car has 190K on it.

There wouldn't be any kind of sensor, that if bad, would cause no power to the injectors?

Tomorrow can try more to see if they are getting pulse and check the fuel pressure with a gauge but for now have to ask questions in hypotheticals.
Thanks guys.

You are on the right track here. No sensor will stop the injectors from opening during the prime sequence for startup. This is exactly why you need to verify that the injectors are getting a +12 volt continuous when the key is turned to the on position. The +12 volts are looped from one injector to the other; all the same circuit. Just test one and that's it. This takes about 1 minute to perform.

Next is the fuel pressure...should be > 45psi at the rail when the pump primes. The pressure may bleed down a bit after the pump shuts off. Don't try to start the car and watch the fuel pressure after the key has been turned to the on position. It might lose 10 psi over 10 minutes which is fine.

Here is what you need at the injectors for the car to start:
1) Fuel rail primed
2) Fuel pressure >45 psi
3) +12 volts continuous with key on
4) Commanded ground from the PCM

If you have all of this and it doesn't start then the injectors are bad or clogged. You've already verified that it will run with fuel so all other systems are operating properly.

you have the battery and 2 other O ring grounds that bolt to the trans bell housing bolt. the one that has a stud on the end of it. they bolt in right above the starter, and yes if one was left off it could keep the car from running.

make sure the starter is also wired correctly.

I never would have guessed that in a million years.
Your gonna have to be more careful next time with the wiring.

that's the maf and tps. Which...should be keyed and not possible to mix up. Cool though.

Scotty...next time toss that ground to the trans out sooner. I was 99% sure it was that.
Rico.. pcm pulses ground, not power.

Oops, got it backwards.
Thanks Bill

I'll edit my posts for the next guy.

Easy way to remember it is that in most casese the circuitry of the pcm can't handle power or high power. Therefore it does as much with grounds as possible.

Makes sense. Ground returns are always low power.

I edited the previous posts as to not confuse the next poor guy having a similar problem.

Er uh..the coolant sensor then,. I'll have to take a closer look. I didn't think they'd interchange either.

Originally Posted by stef101

Heres one, battery went dead in my 07 gp 3.8l base. Put new battery in it, cranks but wont start. Hooked up code scanner, comes up with 10 dtcs. 2 o2 circuits, evap cir, and all 6 injection circuits. Any possible ideas. Im thinking something simple. Of coarse im being optimistic.

post the codes.

one may have something to with the others, cant tell by just you saying 10 dtcs.

and with 10 codes you should just start your own thread for your problem. keeps confusion down.

You said you checked fuses, because that sure sounds like one of the supply fuses popped.

Give us a little more background. This a daily driver and the battery went dead, so it was pulled and swapped all in one shot? No other things were undone?

If you have no power to those fuses with the key on, then it's a trace back from there. What feeds the power to those fuses. I assume they are in the under hood relay/fuse center?

You need to trace back the supply to those fuses that you don't see power at. With key on..injectors, o2 sensor etc should have power.

I experienced this myself and wanted to share for those who face the same problem.

I had 12+ to each fuel injector. PCM would not pulse fuel injectors while cranking. If you start the vehicle off ether then the injectors would fire and car would drive.

It ended up being I had a 1 bar MAP instead of a 2 bar MAP installed (GTP top swap on 04). The PCM not reading the correct information from the vehicle sensors, did not spray fuel while cranking but did while running.

So if you have a no fuel injector pulse while cranking issue I would look into the sensors and make sure they are reading correctly, plugged in, etc. Hook up a scan tool and read the live data. Mine never threw a MAP code.